1. Field of the Invention
This invention relates to electronic musical instruments and in particular is concerned with provision for automatically adjusting the level of the accompaniment to follow the dynamics of a solo keyboard.
2. Description of the Prior Art
An all too familiar word to an orchestral musician is the word "balance." It is one of the major tasks of the conductor to maintain a constantly changing balance between the loudness of those instruments having the most important musical passages and those instruments providing the background or accompaniment tones. The ability to balance various simultaneous musical lines is one of the primary attributes of the conventional acoustic piano. A skilled pianist has the capability of playing any desired notes in a balanced loudness relation with respect to the other notes.
Electronic keyboard actuated musical instruments, of the type given the generic name of "organ" suffer from the same type of musical balance problems experienced with conventional wind-blown organs. The balance problem is caused by the action by which a stop is either full "off" or full "on." Each stop controls a tone selection for the organ. Each stop not only changes the tone variety or tone color but in general the loudness of each stop is usually designed to be independent of the loudness of the other stops. If the stops for the solo keyboard are changed it frequently results in an accompaniment on the other keyboard or the pedal board which is either too loud or too soft with respect to the solo voices. The player usually has three options of means to correct the balance between the solo and accompaniment voices. He can change the accompaniment stops when the solo stops are changed and thereby attempt to reach a compromise in the desired solo tone color and the loudness and tone color of the accompaniment. Such a technique, although frequently used, requires considerable skill on the part of the musician. To be even moderately successful in obtaining a loudness balance, he must be very familiar with the available tones and their relative loudness for a number of combination stops. A second balance option is to use electronic controls which independently vary the loudness of each keyboard. While such controls seem to provide a good solution to the problem of balance, in practice it requires that each change in the stops for any keyboard dictates that changes must be made to the loudness controls of the other keyboards. Such an ideal balance technique is usually beyond the capability of all but the most skillful musicians. Even when independent loudness controls are available in an organ, all except the best players tend to ignore the balance of musical lines and simply change the tone colors with the stops and "live" with the resultant relative loudness of the keyboards. It is such subtle differences in balance that distinguish a mediocre performance from a good performance in which by careful attention to tonal and loudness balance the musician sets the mood of the musical passages.
Various electronic organs have been designed in which the stops can be used to select a tone color and at the same time control the loudness of the tone. The most familiar of such systems is the one using a set of drawbars each of which selects the loudness of a harmonic associated with an actuated keyboard switch. A system of this type is discussed in U.S. Pat. No. 3,636,231 entitled "DC Keyed Synthesis Organ Employing An Integrated Circuit." With this arrangement it is possible to control the tone color by the setting of nine controls. After a tone color is selected, the loudness can be changed by moving all the drawbars simultaneously. The loudness change is not easy to accomplish without changing the tone color and in practice the drawbars are only used to vary the tone color.
A system for using a single stop to control both the selected tone and its relative loudness is described in U.S. Pat. No. 3,823,390 entitled "Musical Tone Wave Shape Generating Apparatus." In theory the stop control system described in the patent can be used to adjust the loudness of each selected tone color. In practice one finds that it is impossible to maintain a balance during a performance because the player does not have sufficient time to selectively set the level of each stop control. The musician usually actuates these stops to their full on or full off position so that the property of individual stop loudness controls is completely wasted.
It is an object of this invention to provide means for automatically maintaining a selected loudness balance between keyboards.
It is a further object of this invention to maintain a selected balance which is adaptive to the number of notes actuated on each of the keyboards.